''He raised his hand up, and then while he was raising his hand up we saw another attack pull him in the water.

''He came back up, his head was on the water … then we noticed he was already dead.''

He heard the police then fire shots from their helicopter, and also heard a few shots from a lifeguards' boat. ''I don't know if they got the shark, killed the shark or not,'' Mr Mose said.

There have been 14 known fatal shark attacks in New Zealand since records began about 1837, said the department's shark expert, Clinton Duffy.

''In the last 20 years we have been averaging two shark incidents, where the shark actually bites someone, a year,'' Mr Duffy said.

''Those are generally on swimmers and generally result in fairly superficial flesh wounds.''

The last death was in 2009, when a kayaker was mauled by a great white in Coromandel waters - although whether he drowned before the shark found him is still disputed. Before that the last death was in 1976.

Shark attacks around the world have increased every decade since 1900. Last year's tally of 12 fatalities, with three in Australia, was almost three times the average of 4.3 from 2001 to 2010, according to the International Shark Attack File.